The fourth act is played in front of the Lateran church. The battle has taken place. The barons have been repulsed at the cost of great slaughter. But notwithstanding their losses and the death of their leader, the elder Colonna, the nobles have not relinquished all hope of success. What they failed to secure by the force of arms, they now hope to win by intrigue, for they have artfully won not only the Pope, but the Emperor also, to uphold their cause and side with them. The people, who have just learned that the Pope and Emperor have recalled their legates and ambassadors, are awed and frightened. Baroncelli and Cecco, two demagogues, seize this occasion to poison their fickle minds, and blame Rienzi openly for all that has occurred. Their specious reasoning that the Tribune must be very wicked indeed, since the spiritual and temporal authorities alike disapprove of him, is strengthened by the sudden appearance of Adrian, who, wild with grief at his father's death, publicly declares he has vowed to slay the Tribune. The people—who, lacking the strength to uphold their convictions, now hate their leader as vehemently as they once loved and admired him—are about to join Adrian in his passionate cry of ‘Down with Rienzi!’ when the cardinal and his train suddenly appear, and march into the church, where a grand ‘Te Deum’ is to be sung to celebrate the victory over the barons.
While the Romans are wavering, and wondering whether they have not made a mistake, and whether the Pope really disapproves of their chief magistrate, Rienzi marches toward the church, accompanied by Irene and his body guard. Adrian, at the sight of his pale beloved, has no longer the courage to execute his purpose and slay her only brother. Just as they are about to enter the church, where they expect to hear the joyful strains of thanksgiving, the cardinal appears at the church door, barring their entrance, and solemnly pronounces the Church's anathema upon the horror-struck Rienzi.
The people all start back and withdraw from him as from one accursed, while Adrian, seizing Irene's hand, seeks to lead her away from her brother. But the brave girl resists her lover's offers and entreaties, and, clinging closely to the unhappy Tribune, she declares she will never forsake him, while he vows he will never relinquish his hope that Rome may eventually recover her wonted freedom, and again shake off the tyrant's yoke.
The fifth and last act is begun in the Capitol, where Rienzi, the enthusiast, is wrapped in prayer, and forgetting himself entirely, fervently implores Divine protection for his misguided people and unhappy city. He has scarcely ended this beautiful prayer when Irene joins him, and, when he once more beseeches her to leave him, she declares she will never forsake him, even though by clinging to him she must renounce her love,—a passion which he has never known. At this declaration, Rienzi in a passionate outburst tells how deeply he has loved and still loves his mistress, Rome, fallen and degraded though she may be. He loves her, although she has broken faith with him, has turned to listen to the blandishments of another, and basely deserted him at the time of his utmost need.
Irene, touched by his grief, bids him not give way to despair, but adjures him to make a last attempt to regain his old ascendency over the minds of the fickle people. As he leaves her to follow her advice, Adrian enters the hall, wildly imploring her to escape while there is yet time, for the infuriated Romans are coming, not only to slay Rienzi, but to burn down the Capitol which has sheltered him.
As she utterly refuses to listen to his entreaties, he vainly seeks to drag her away. It is only when the lurid light of the devouring flames illumines the hall, and when she sinks unconscious to the floor, that he can bear her away from a place fraught with so much danger for them all. Rienzi, in the mean while, has stepped out on the balcony, whence he has made repeated but futile attempts to address the mob. Baroncelli and Cecco, fearing lest he should yet succeed in turning the tide by his marvellous eloquence, drown his voice by discordant cries, fling stones which fall all around his motionless figure like hail, and clamour for more fuel to burn down the Capitol, which they have sworn shall be his funeral pyre. Calmly now Rienzi contemplates their fury and his unavoidable death, and solemnly predicts that they will regret their precipitancy, as the Capitol falls into ruins over the noble head of the Last of the Tribunes.
SENTA.